Answer : Option C

Explanation :

distance = speed x time
Let time taken to travel the first half = x hr
then time taken to travel the second half = (10 - x) hr
Distance covered in the the first half = 21x
Distance covered in the the second half = 24(10 - x)
But distance covered in the the first half = Distance covered in the the second half
=> 21x = 24(10 - x)
=> 21x = 240 - 24x
=> 45x = 240
=> 9x = 48
=> 3x = 16

$MF#%\begin{align}
&\Rightarrow x = \dfrac{16}{3}\\
&\text{Hence Distance covered in the the first half = }21x = 21 \times \dfrac{16}{3} = 7 \times 16 = 112\text{ km}\\
&\text{Total distance = }2 \times 112 = 224\text{ km}\\
\end{align} $MF#%